Description (as provided by the applicant): Support is requested for a Keystone Symposia meeting entitled Emerging Topics in Immune System Plasticity: Cellular Networks, Metabolic Control, and Regeneration, organized by Steven L. Reiner, Erika L. Pearce and Yasmine Belkaid. The meeting will be held in Santa Fe, New Mexico from January 15 - 20, 2013. The immune system is a multi-cellular network that adapts to external threats. Immune cells cooperate with other defenses, such as barriers, to prevent breach and to reject invaders by selecting the right responses while inflicting minimal damage to the host. A key feature of the immune system is its fluidity and ability to traverse temporal and spatial boundaries. Furthermore, immune system dynamics involve cellular expansion, provisional cellular niches, altered transcription, and balancing differentiation with regeneration. This meeting will bring together diverse researchers to better understand how immune reactions are orchestrated to contend with the extrinsic information and metabolic demands of cellular differentiation, function, and homeostasis. The aims of the meeting are to 1) unveil the nature of cell-to-cell communication that occurs during different stages of the immune response, 2) reveal the latest understanding of extrinsic and intrinsic signaling networks that dictate lymphocyte and other immune cell fates, 3) increase awareness of metabolic control of immune cell fate and function, and 4) provide a format for the training and mentoring of new investigators and pre- and post- doctoral students. We anticipate that this meeting will alter the field's view of immune mobilization and execution, and will help to break barriers between immunology and other disciplines.